1. Field of the Invention
The present invention relates to an opening and closing apparatus which opens and closes a gate by using a moving body, and relates to an excellent opening and closing apparatus for a sliding door, a back door or the like of a vehicle, which apparatus is driven by a motor.
2. Description of the Related Art
At sliding door apparatuses which are employed for opening and closing rear seat passenger entrances (gates) in vehicles such as station wagons, vans, sports utility vehicles and the like, there is a trend to using automatic sliding door apparatuses, in which a door panel is moved to open and close by a driving force of a motor or the like.
The vehicles mentioned above often have structures in which a “luggage room” and a passenger space for occupants are not partitioned but unified. In such a vehicle, a back door which rotates about an axis, whose axial direction is substantially in the vehicle width direction, at an upper end vicinity of the vehicle may be provided to correspond to a rear gate. The back door rotates upward and downward, and thus the rear gate opens and closes.
With such back door apparatuses, operations of opening and closing the back door have hitherto been carried out by manual operations. However, because the back door is moved to the upper side of the vehicle when the rear gate is in the open state, operation when the rear gate is to be closed is troublesome. In particular, the operation of closing the back door is arduous if the person carrying out the opening and closing operations is short in stature. Accordingly, there have been earnest demands for automatic opening and closing using driving force of a motor or the like, similarly to sliding doors. (Refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-280000 for an example of a structure which opens and closes a back door by driving force of a motor.)
In accordance with the automation of opening and closing operations of back doors as described above, redeployment of trapping detection devices, which have hitherto been employed for detecting foreign objects trapped by door panels in automatic sliding door apparatuses, in the automatic back door apparatuses has been considered.
At a trapping detection device assembled to an automatic sliding door apparatus, a pressure sensor is disposed along an end portion at a closing direction side of a door panel. If the door panel traps a foreign object between the door panel and an inner periphery portion of the passenger opening while moving to close, and the door panel applies pressure to the foreign object, a reactive pressure force from the foreign object is detected by the pressure sensor.
Among such pressure sensors, a pressure sensor in which long strip-form electrode sheets are disposed to oppose one another across a gap is typical (below, this type of pressure sensor is referred to as a “facing sensor” where appropriate). The exteriors of these electrode sheets are covered with rubber or the like except at the gap between the electrode sheets. (Refer to JP-A No. 9-318467 for an example of a facing sensor.)
In contrast, there is also a pressure sensor in which long cord-form electrode wires which are wound helically, with a length direction being an axial direction of the helical form, are disposed to oppose one another across a gap, in a direction intersecting the length direction (below, this kind of sensor is referred to as a “helical sensor” where appropriate). (Refer to JP-A No. 10-228837 for an example of a helical sensor.)
In vehicles such as vans, sports utility vehicles and the like, the external outlines of back doors are becoming more complex for various reasons, such as improving the appearance of the vehicle, increasing rear illumination from brake lamps and the like which are disposed at both sides of a rear portion of the vehicle, and the like. In particular, a back door is formed such that a boundary between the back door and a main body portion of the vehicle at an upper portion of the back door relative to a vertical direction central portion of the vehicle, which boundary is located at an upper side relative to a lamp housing which accommodates a rear illuminator, is formed so as to face outward in the width direction of the vehicle.
In contrast, at a lower side relative to the above-mentioned central portion, the back door is positioned between lamp housings at both sides of the vehicle. Here, the back door is formed such that the boundary between the main body portion of the vehicle and the back door faces rearward of the vehicle.
As described above, structures have emerged in which the external outline of the back door is inflected in three dimensions, in addition to which a large number of angle portions are present. (Please refer to FIGS. 1 to 7, which are used for description of an embodiment of the present invention, for details of the shape of such a back door.)
In the facing sensor described earlier, the facing direction is a single direction. Thus, if a facing sensor is disposed along the whole of the outer periphery portion of a back door with a structure in which the outer periphery portion is inflected in three dimensions, there will be portions at which the facing direction of the electrode sheets is not oriented in an opening/closing direction of the back door. Therefore, of pressure sensors, the facing sensor cannot be applied to this back door.
In contrast, in the case of a helical sensor, when an external force acts from a direction which is inclined relative to the length direction of the helical sensor, the sensor resiliently deforms, the electrode wires make contact, and the external force can be detected. Therefore, even with a back door with a structure whose outer periphery portion is three-dimensionally inflected, it is possible to dispose a helical sensor along the whole of the outer periphery portion.
However, because this helical sensor is a structure which detects an external force when the sensor is resiliently deformed by an external force and the electrode wires make contact as described above, if the helical sensor is disposed along the angle portions of the three-dimensionally inflected outer periphery portion of the backdoor, there is a possibility that the sensor will be inflected and resiliently deformed thereat, and that the electrode wires may make contact because of this resilient deformation.
Accordingly, with a back door structure whose outer periphery portion is inflected in three dimensions, it is extremely difficult to dispose a pressure sensor along the outer periphery portion.